Technical Science - Term 4 - Week 10

An electrical circuit is a closed loop that allows electric current to flow. The main components of a circuit include a power source (like a battery), conductors (wires), and load devices (like bulbs or resistors). Understanding how these components interact is crucial for analyzing and designing circuits.

There are two primary types of circuits: series and parallel. In a series circuit, components are connected end-to-end, meaning the same current flows through all components. In contrast, a parallel circuit has components connected across common points, allowing multiple paths for current to flow. This distinction affects how voltage and current are distributed in the circuit.

Ohm's Law is a fundamental principle in electronics that relates voltage (V), current (I), and resistance (R) in a circuit. It is expressed as V = I × R. This law allows us to calculate one of these values if the other two are known, making it essential for circuit analysis.

Consider a series circuit with a 12V battery and two resistors of 4Ω and 6Ω. The total resistance (R_total) is R1 + R2 = 4Ω + 6Ω = 10Ω. Using Ohm's Law, the current (I) can be calculated as I = V / R_total = 12V / 10Ω = 1.2A. Thus, the same current flows through both resistors.

In a parallel circuit with a 12V battery and two resistors of 4Ω and 6Ω, the total resistance (R_total) can be calculated using the formula 1/R_total = 1/R1 + 1/R2. This gives us 1/R_total = 1/4 + 1/6, leading to R_total = 2.4Ω. The current through the circuit can then be calculated as I = V / R_total = 12V / 2.4Ω = 5A.

Let's work together on a problem. We have a series circuit with a 9V battery and two resistors of 3Ω and 5Ω. First, calculate the total resistance. Then, use Ohm's Law to find the current flowing through the circuit. Remember to add the resistances first and then apply the formula I = V / R_total.

Now, try these problems on your own. Problem 1: A circuit has a 15V battery and three resistors in series: 2Ω, 3Ω, and 5Ω. Calculate the total resistance and the current. Problem 2: A parallel circuit has a 10V battery and two resistors of 5Ω and 10Ω. Find the total current flowing through the circuit.

• Volts
• Amperes
• Ohms
• Watts

Answer: Ohms

Resistance is measured in Ohms, which quantifies how much a material opposes the flow of electric current.

• The same through all components
• Different for each component
• Zero
• Varies with voltage

Answer: The same through all components

In a series circuit, the same current flows through each component because there is only one path for the current.

Answer: V = I × R

Ohm's Law states that voltage (V) is equal to the current (I) multiplied by the resistance (R).

• It increases
• It decreases
• It stays the same
• It doubles

Answer: It decreases

Adding more resistors in parallel provides additional paths for current, which decreases the total resistance.

Answer: 4A

Using Ohm's Law, I = V / R = 20V / 5Ω = 4A.

• Resistor
• Capacitor
• Inductor
• Transistor

Answer: Capacitor

A capacitor is designed to store electrical energy temporarily in an electric field.

Answer: 25Ω

In a series circuit, total resistance is the sum of individual resistances: 10Ω + 15Ω = 25Ω.